The present invention relates to a mobile type X-ray apparatus, and more particularly, to an X-ray apparatus which includes a power driving type truck moving forward or backward in response to a force of an operation handle.
FIGS. 3(a) through 3(c) show a conventional mobile type X-ray apparatus or X-ray photographing apparatus with a cordless inverter system for a circuit examination by a doctor. FIG. 3(a) shows a front view; FIG. 3(b) shows a side view; and FIG. 3(c) shows a plan view thereof. The X-ray photographing apparatus includes an X-ray tube 17; an arm 13 for supporting the X-ray tube 17; a column 14 freely rotatable on a truck or main body 1; and an ascending and descending section, in which the arm 13 moves vertically or up and down along the column 14. The truck 1 is provided with freely pivotable front wheels 11 and rear wheels 12 incapable of steering. The truck 1 also includes a controller, and is moved forward or backward by driving motors 18 by operation of an operation handle 3 forwardly or backwardly, which is provided at handle supporting bases 2 attached to the truck 1.
The arm 13, which includes a supporting mechanism for the X-ray tube 17 and a rotating mechanism therefor, and extends or retracts in a horizontal direction, is designed to move vertically along the column 14 smoothly so as to be balanced. In the apparatus, a collimator (X-ray radiation port) of the X-ray tube 17 is directed to portions of a subject to be photographed, i.e. a person to be examined, from all the directions in all spatial positions.
Since the weight of the movable type X-ray photographing apparatus may become more than 450 kg, it is extremely difficult to move the truck without a help of the power. Generally, a pair of the rear wheels 12, which are fixed not to change directions, is provided at a rear portion of the truck 1, and a front portion of the truck 1 is supported by a pair of casters, that is, freely pivotable from wheels 11. The rear wheels 12 are generally driven by the driving motors 18 attached to the truck.
The truck 1 includes an internal power supply with a main circuit of 100 to 120 V and 60 Hz, which is formed of a battery and an inverter, and the truck 1 also includes a high-voltage transformer and an inverter control device. In many cases, there is used an apparatus of a one-touch system, wherein a control circuit thereof is systematized and a photographing operation is automatically programmed.
Also, the truck 1 is designed to have rubber tires such that the truck 1 can freely enter or leave a patient""s room, an operating room, and an elevator, and the truck 1 is further provided with a brake system, a cassette box, and accessories.
It is important that the movable X-ray photographing apparatus is small, light-weighted, and excellent in a moving operation ability as a mobile type apparatus, and the movable X-ray photographing apparatus is easily moved to a bedroom, an operating room, a children room or a pediatric room, an X-ray room, an infant room or the like in a hospital, and conveniently used for an X-ray photographing or radiography at a working site, that is, the location where the apparatus is moved.
FIG. 4 shows a diagram of a control system of the conventional mobile type X-ray apparatus. The truck or frame 1 is shown at an upper side in FIG. 4, and a left rear wheel 12a and a right rear wheel 12b are respectively driven by a left driving motor 18a and a right driving motor 18b. The left driving motor 18a and the right driving motor 18b are individually controlled by a control board 19. In the control board 19, control signals are supplied from a corresponding left side sensor signal processing circuit and a corresponding right side sensor signal processing circuit. These two electronic circuits adjust signals, which are issued from a left advancing pressure sensor 6af, a left retreating pressure sensor 6ab, a right advancing pressure sensor 6bf, and a right retreating pressure sensor 6bb due to corresponding forces, to signals appropriate for applying to the Left driving motor 18a and right driving motor 18b. T hen, rotational speeds from the left driving motor 18a and the right driving motor 18bare respectively detected by a left pulse encoder 19a and a right pulse encoder 19b, and signals thereof are fed back to the control board 19, so that the control is carried out to have appropriate driving speeds.
In this electrically powered mobile type X-ray apparatus, a power from an output shaft of a rotor in the driving motor 18 is transmitted to the rear wheel 12 through a decelerating mechanism. As the decelerating mechanism, there are a mechanism wherein a planetary gear type decelerator is embedded in the driving motor 18, and a mechanism wherein a planetary gear decelerating mechanism is built inside the rear wheel 12.
FIG. 5 shows a planetary gear mechanism. The planetary gear mechanism is a mechanism such that in a pair of gears engaging each other (sun gear 4 and planetary gear 5), the two gears respectively rotate on their own axes, and at the same time, one of the gears (planetary gear 5) revolves around the axis of the other gear (sun gear 4). The gear, which not only rotates on its own axis but also revolves at the revolving axis, constitutes the planetary gear 5; the gear, wherein a position of the axis thereof does not change, constitutes the sun gear 4; and a member for supporting the planetary gear 5 constitutes a carrier 8. One of an internal gear 7, the sun gear 4 and the carrier 8, which are provided coaxially, is fixed, and the other two are used as input and output axes to have functions of deceleration, acceleration, and reversing.
The conventional mobile type X-ray apparatus is structured as described above. However, in the apparatus, wherein the planetary gear type decelerator is embedded as the decelerator in the driving motor 18, in order to transmit the power from the output shaft of the rotor inside the driving motor 18 to the rear wheel 12, according to the structure thereof, a gear sound of meshing the gears is generated, resulting in a problem in case the apparatus is moving in a quiet place inside the hospital.
Also, in the apparatus in which the planetary gear type decelerator is embedded, since a backlash is large, an operator can not control the apparatus desirably, resulting in a problem that a positioning of the apparatus at a bed side in a narrow patient""s room is difficult.
On the other hand, in case the decelerating mechanism is built in the rear wheel 12, it is necessary to transmit the power by a belt between the driving motor 18 and the rear wheel 12, so that an occupied volume of the driving section is increased.
The present invention has been made in view of the foregoing, and an object of the invention is to provide a mobile type X-ray apparatus, which includes a compact decelerating mechanism and can be moved in a quiet condition, that it, in the condition that the gear sound of meshing the gears is not generated.
Another object of the invention is to provide a mobile type X-ray apparatus as described above, which can be easily operated by an operator, in other word, which has no difficulty in operation due to the backlash as in the conventional apparatus.
Further objects and advantages of the invention will be apparent from the following description of the invention.
To achieve the above objects, the present invention provides a mobile type X-ray apparatus, which comprises a pair of right and left driving motors; a pair of cyclo-decelerating mechanisms respectively built in the driving motors; and a pair of driving wheels respectively attached to the cyclo-decelerating mechanisms. The driving wheels are individually driven by the respective motors through the respective cyclo-decelerating mechanisms in response to an operation power in a direction applied to an operation handle.
The mobile type X-ray apparatus is structured as described above, and in order to transmit the power of the driving motor to the wheel, the cyclo-decelerating mechanism is provided inside the driving motor and connected to the axis of the wheel. Thus, the power is transmitted by an eccentric wheel and rollers in the cyclo-decelerating mechanism, so that the apparatus can be moved quietly without making a noise. Also, since the backlash is small, the operation ability of the apparatus is improved. Further, since the cyclo-decelerating mechanism is built in the driving motor and connected to the axis of the wheel, the apparatus can be structured to be compact.